A microsatellite locus can show linkage to a disease gene

A PCR banding pattern is shown for a family with six children, and this pattern is interpreted at the top of the illustration with the use of four different-size microsatellite “alleles,” M′ through M″″. One of these markers (M″) is probably linked in cis configuration to the disease allele P. (Note: This mating is not a testcross, yet is informative about linkage.)